Thanks for the reply! I'm pretty sure it's spark. When it dies it's like the key is shut off, no sputtering it just instantly shuts off. When I go to restart it it will crank and crank with no sign of wanting to start, and then it will just fire right up and run perfectly. When it happens cruising down the highway with the converter locked up, it will die and then 20-30 seconds later it restarts itself. It didn't happen at all today. Yesterday it did it 3 times within about 5 minutes and then ran perfectly the rest of the way home. It doesn't throw any codes, I checked.